Static reservoir characterization of shallow marine carbonate rocks: A case study from the Late Triassic-Early Jurassic Sarki Formation, NE Iraq

Abstract
This study investigates the reservoir properties of the Late Triassic-Early Jurassic shallow marine carbonate\r\nSarki Formation outcrop, specifically in the Zarwan section of northeastern Iraqi Kurdistan. The lithology of the studied\r\nsection comprises dolomite, dolomitic limestone, recrystallized breccia and thin beds of marls, with a formation thickness of\r\napproximately 115 m. Various techniques, including microscopic study, core plug analysis and scanning electron microscopy\r\n(SEM) were employed to assess reservoir properties. The Sarki Formation consists of diverse pore types, including vuggy,\r\nmoldic, intraparticle, interparticle, fracture, intercrystalline, stylolitic and microporosity. Identified diagenetic processes\r\ninclude early dolomitization, compaction (physical and chemical), cementation (granular, blocky, and drusy cements),\r\nmicritization, dissolution, silicification, neomorphism, late dolomitization, and fracturing. Petrographic analysis indicated\r\na porosity average of 2% in the lower part of the formation and 6% and 9.5% in the middle and upper parts, respectively.\r\nA scanning electron microscopy (SEM) study confirmed similar porosity values with micropore sizes in the studied\r\nsection. Core plug analysis results were roughly aligned with optical assessments, revealing porosity values of 2%, 6%,\r\nand 10% for the lower, middle, and upper parts, respectively. Overall, the Sarki Formation exhibited negligible to fair\r\nporosity ranges. Permeability measurements values averaged 0.01 md, 0.02 md, and 0.13 md for the lower, middle, and\r\nupper parts respectively, indicating a poor to fair permeability range. The upper part of the formation was deemed to have\r\nfair reservoir quality due to fewer observed diagenetic processes than the middle and lower parts, although permeability\r\nmay be relatively low. In contrast, the lower and middle parts displayed poor reservoir characteristics, suggesting limited\r\npotential in the context of the petroleum reservoir.

Author
Irfan Shaaban Asaad

DOI
https://doi.org/10.7186/bgsm79202509

Publisher

ISSN
0126-6187

Publish Date: